tea-aroma-analysis-based-on-solvent-assisted-flavor-evaporation

Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment

Tea aroma is an important factor in tea quality, but it is challenging to analyze due to the complexity, low concentration, diversity, and lability of the ...

Tea Research Institute Chinese Academy of Agricultural Sciences

The physicochemical characteristics, sensory quality, and antioxidant activity of tea infusions prepared with purified water (PW), mineral water (MW), mountain spring water (MSW), and tap water (TW) from Hangzhou were investigated. The results showed that the taste quality, catechin concentration, and antioxidant capacity of green, oolong, and black tea infusions prepared using MW and TW were significantly lower than those prepared using PW. Extraction of catechins and caffeine was reduced with high-conductivity water, while high pH influenced the stability of catechins. PW and MSW were more suitable for brewing green and oolong teas, while MSW, with low pH and moderate ion concentration, was the most suitable water for brewing black tea. Lowering the pH of mineral water partially improved the taste quality and increased the concentration of catechins in the infusions. These results aid selection of the most appropriate water for brewing Chinese teas.

Effect of the type of brewing water on the chemical composition, sensory quality and antioxidant capacity of Chinese teas.

Green tea processed from autumn leaves is more bitter and astringent than that from spring leaves, mainly due to gallated catechins. The present study aimed to improve the taste of autumn green tea and green tea infusion by using tannase to treat tea leaves and tea infusion. The results showed that, after hydrolysis, the sweet aftertaste and overall acceptability improved, and the ratio of gallated catechins decreased, as did the bitterness and astringency of the autumn green tea. The pH value was significantly correlated with the concentrations of gallated catechins (r = 0.930, p < 0.01), non-gallated catechins (r = -0.893, p < 0.01), and gallic acid (r = 0.915, p < 0.01), as well as with the intensities of bitterness, astringency, and sweet aftertaste during hydrolysis. Gallic acid contributed to the sweet aftertaste of green tea infusion. These results will help to improve autumn green tea products with tannase.

Improving the taste of autumn green tea with tannase.

Zijuan tea is a representative anthocyanin-rich tea cultivar in China. In this study, Zijuan tea was used to produce a novel kombucha beverage (ZTK). The physicochemical, sensory properties, and antioxidant activity of ZTK were compared with that of black tea kombucha (BTK) and green tea kombucha (GTK). Results indicated that after fermentation, the color of ZTK changed from yellowish-brown to salmon-pink, because its anthocyanins (4.5 mg/L) appeared red in acidic conditions. Meanwhile no significant changes of color were observed in BTK and GTK. The dynamic changes of pH, biomass, and concentrations of sugars, amino acids, and main organic acids were similar in three kombucha beverages, except catechins showing different trends. Moreover, ZTK showed the highest overall acceptability score, antioxidant activity, and concentration of volatiles among the three kombucha beverages. Therefore, Zijuan tea is suitable for the preparation of kombucha beverage with attractive color and health benefits.

Zijuan tea- based kombucha: Physicochemical, sensorial, and antioxidant profile.

The effects of β-glucosidase on the volatile profiles and aroma stability of black tea juice were evaluated using gas-chromatography-mass spectrometry coupled with sensory analysis. During liquid fermentation of tea leaves, the addition of β-glucosidase increased the concentration of aldehydes, strengthening the undesirable "green grassy" odour. However, the "green grassy" odour was counteracted by adding green tea extract during fermentation. At the same time, "flowery" flavour notes were enhanced, improving the overall aroma quality and strengthening the characteristic "sweet" aroma of black tea. Increased addition of β-glucosidase released more free aroma alcohols from their glucosides. Two "fruity" and "floral" aroma components, benzyl alcohol and phenylethyl alcohol, were not significantly affected by heat treatment (95 °C water bath) and the overall aroma stability was not significantly affected by β-glucosidase treatment. β-Glucosidase treatment improved the aroma, colour and overall suitability of fermented black tea juice as an ingredient for tea-based beverages.

Effect of β-glucosidase on the aroma of liquid-fermented black tea juice as an ingredient for tea-based beverages.

Tea is the main raw material for preparing tea wine.

Impact of tea leaves categories on physicochemical, antioxidant, and sensorial profiles of tea wine.

Hops provide the characteristic bitter taste and attractive aroma to beer; in this study, hops were replaced by jasmine tea extract (JTE) during late-hopping. The addition of JTE improved the beer foam stability 1.52-fold, and increased the polyphenol and organic acid contents. Linalool was the most important aroma compound in hopped (HOPB) and jasmine tea beer (JTB), but other flavor components were markedly different, including dimeric catechins, flavone/flavonol glycosides, and bitter acids and derivatives. Sensory evaluation indicated that addition of JTE increased the floral and fresh-scent aromas, reduced bitterness and improved the organoleptic quality of the beer. The antioxidant capacity of JTB was much higher than that of HOPB. The inhibition of amylase activity by JTB was 30.5% higher than that of HOPB. Functional properties to beer were added by substituting jasmine tea extract for hops during late hopping.

Chun Zou

Tea Research Institute Chinese Academy of Agricultural Sciences

Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment